Talk:Population signature
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Notability
Is this concept notable enough for a dedicated page? I wonder if there is a non-LifeWiki usage of the term "signature". GUYTU6J (talk) 08:14, 7 August 2022 (UTC)
- Agree. The concept never got traction and apgcode is a far better identifier Book (talk) 23:57, 17 August 2022 (UTC)
- The idea of a population signature is very old -- for example, that's what "Cambridge pulsar CP 48-56-72" is, and more recently population signatures have been used in search scripts, such as Chris Cain's popseq. They aren't often called "signatures" these days; at least, I'm more likely to call them "population hashes", since population amounts to an isotropic hash function for active reactions (though there can be a lot of false positives due to "hash collisions" in some cases).
However, the most common use of "signature" that I can find is from the early 1990s, and it involves counts of neighbors in babbling-brook oscillators:
From: Dean Hickerson<br> Date: Thu, 10 Nov 1994 00:48:43 +0800<br> Subject: Babbling brooks Mostly to Bob Wainwright and Mark Niemiec rtw> In the meantime, what is a "babbling brook"? It's an oscillator in which the set of active cells forms a chain, with each cell adjacent only to its 1 or 2 neighbors in the chain. The term was introduced by Allan Wechsler in a 9/8/94 message, in which he also introduced "rotor" and "stator": acw> I have a new nomenclature that I'm trying to force on the community by > using it a lot: I call the active cells the "rotor" and the unchanging > ones the "stator", in analogy with the parts of an electric motor. > > So you want to know if there is any long-period oscillator whose rotor > is a chain. We might call these "babbling brooks". We can specify how a babbling brook works by specifying its "signature" and the state of the rotor in gen 0. The signature is a list of numbers from 1 to 3 indicating for each cell of the rotor how many live neighbors it has in the stator. There are essentially only 3 known babbling brooks, although each has more than one realization as a Life pattern. Two are p2 and one is p4; they're described abstractly as follows: signature period gen 0 gen 1 gen 2 gen 3 --------- ------ ----- ----- ----- ----- 33 2 .. oo 333 2 ... ooo 3113 4 ..oo o.o. oo.. .o.o Examples of the first are the beacon and the spark coil; note that the shape of the rotor is different for these. For the second p2, there are 4 possible rotor shapes but only one can be realized in Life; "light bulb" from LifeLine 3:3 is an example, as is this smaller implementation of it: ...o..... .ooo..... o........ oooooo... ......o.. ..o...o.. ..oo.o... ......ooo ........o For the p4, 4 of the 12 possible rotor shapes can be realized: .....oo..... ....o.o..... .o..o....... ....oo..... o.o.o....... ...o.o..... .o..o....... ...oo...... ...o....... ....o.oo..oo .....o...... ..o..o..... oo.o....... .....o..o..o ...ooooo..oo .o.o..o..oo oo.o..o..oo ......ooooo. o.o.....o..o o..o...o..o ...o.o.o..o ............ oo.o..ooo.o. oo..oooooo. ...o..oooo. ........o... ...o.o..o.oo ........... ..oo....... .......o.o.. ...o..oo.... ......oo... ......oo... ........o... ..oo........ ......oo... ......oo... Mark Niemiec wrote a program to try to find other babbling brooks. He found several possibilities with periods 3, 5, 6, 8, 9, and 10, but it's doubtful that any of them can be realized in Life. While we're on the subject of oscillators with simple rotors, here's a p4, called "wavefront", from Buckingham's collection: ........oo ........o .........o ........oo .....oo...oo ....o..ooo..o ....o.....oo .....o...o oo.o.o...o o.oo.o.oo ....o.o ....o.o .....o The rotor consists of 3 symmetric pairs of cells along a diagonal: a a b b c c The signature is 322 and the 4 phases are ..., o.., .o., and .oo . I wonder if there are other examples of this with period larger than 2. Mark, could your program be modified to look for such things?
If the "signature" article is kept, maybe it should disambiguate these two uses of the word. Dvgrn (talk) 15:04, 18 August 2022 (UTC)
With these highly specific usage (the original period-5 oscillator tabulation and the babbling brooks research above), the term "signature" now feels like an ordinary word out of dictionary, invoked casually in different contexts when referring to "a code defined such-and-such for this aspect of pattern identification", rather than a common piece of jargon needing a standalone article to introduce. GUYTU6J (talk) 16:32, 18 August 2022 (UTC)
- Agree. It is not a term with specific Life or CA meaning, it's use is generic. Book (talk) 21:00, 18 August 2022 (UTC)
- I think there should be a place in LifeWiki where it is explained what "48-56-72" means in "Cambridge pulsar CP 48-56-72". It seems this idea and this notation for it are sufficiently interesting and useful to warrant a glossary page. I am not sure how to name the page best - something like Population signature could be better. Confocal (talk) 03:38, 19 August 2022 (UTC)
- It seems there is a confusion between the basic idea of writing down the population sequence of an oscillator, the notation used to write it down (hyphenated integer numbers), and the term used to refer to this idea and/or this notation.
- I think this idea and this notation certainly warrant a dedicated glossary page explaining them. Putting the explanation in one of pages where the idea-and-notation is used has the obvious disadvantage that the explanation is misplaced, and then you are forced to either copy-and-paste the explanation of the idea-and-notation everywhere the same idea-and-notation is used, or you are forced to invent roundabout ways to link to that misplaced explanation from other pages without having a dedicated page for it.
- Replying to an earlier comment on this talk page: claiming "apgcode is a far better identifier" is incorrect, because the subject of this page is not an identifier - as far as I can tell, something like "028-35-31-32-33" was never intended (and should not be expected) to be an unambiguous identifier - it is merely a convenient way to specify the sequence of populations. Confocal (talk) 10:54, 19 August 2022 (UTC)
- Good discussion. I first started the article, then thought it was not worth an article, then was persuaded by Confocal's arguments that it has merit. I think calling it "population signature" is accurate and sufficient disambiguation for other uses of "signature" and the def captures its use as reflected in several wiki pages. Just edited to add some of Dave's useful info as well. Still a stub? Book (talk) 20:10, 31 December 2022 (UTC)